Stainless Steel bolts in aluminium.

[Chris Wilson]

Hi all, I am in the process of swapping out any fixings removed whilst maintaining the bike with stainless steel ones.

One theoretical issue is galvanic reaction between two dissimilar metals causing corrosion.

So far, nothing of note has been witnessed.

Latest drama was removing the sump to do an oil filter change.

The standard mild steel allen head bolts seem to burr out easily and yesterday it was a cold chisel to the rescue to remove the worn bolts and replace with stainless.

Anyone out there have issues with stainless?

Thanks, Chris.

[Tomchri]

Had no issues with stainless, but I only use them on light torque places.  Check the sharpness of the treads of the stainless bolts, a fine file, or some 500 paper and a brush, just me.  I use some alu smear for the clean trads in the block. Coud ad 20% of torgue,  so nice and easy does it. And Valpolini gaskest where possible.

Cheers Tom.

[Lucky Phil]

45 minutes ago, Chris Wilson said:

Hi all, I am in the process of swapping out any fixings removed whilst maintaining the bike with stainless steel ones.

One theoretical issue is galvanic reaction between two dissimilar metals causing corrosion.

So far, nothing of note has been witnessed.

Latest drama was removing the sump to do an oil filter change.

The standard mild steel allen head bolts seem to burr out easily and yesterday it was a cold chisel to the rescue to remove the worn bolts and replace with stainless.

Anyone out there have issues with stainless?

Thanks, Chris.

Only that it makes a poor material for a fastener. It's a boating world thing and they need something that can survive a salt laden environment so put up with the negatives. If you want the gold standard in a fastener then use Titanium. All my bikes have a high percentage of Ti fasteners. Light, strong and ductile so they stretch and hold their tension. SS is too hard and lacks ductility so they don't stretch well so lose tension. Ducati tried them as engine cylinder studs at one time and I mean "one time" and had a recall to replace them after they started failing and they were 10mm studs about 180mm long. Junk for fasteners.

Ciao  

[Chris Wilson]

So Phil, all of your bolts and screws are titanium?

I am only replacing bolts to covers that allow maintenance and as noted, at low torque settings or two finger tight leverage.

Things like sump, alternator cover, rack mounts, handlebar mounted equipment etc.

I like the fact that they have a high Rockwell number as I detest turning out the head of an Allen key bolt.

Chris.

[MartyNZ]

Steel bolts fit the price/performance sweet spot. Titanium is almost as strong, lighter, but more expensive, Stainless steel is shiny.

[fotoguzzi]

If the threads were to strip out it won't be the SS bolt, you'll be repairing the engine block or what ever the bolt screwed into. I used to think they were cool.

As to the turning out the Allen head, do you have good hex wrenches? some (craftsman) are just slightly too small for a snug fit. Do you use anti seize? I rarely ever had a problem with Allen heads unless they were in there for 20 or 30 years on some old clapped out Tonti frame.

 

[Chris Wilson]

My guess is that since I have second hand bike with no written history or explanation of how it was used/abused that damage to the maintenance cover fixings happened  pre-purchase.

I have a set of hex drivers that snap onto my socket set ratchet and am running on the assumption that they are indeed the correct and accurate size quoted.

I have had issues with plated drivers being oversize resulting in them being thrown out.

Cheers.

[Lucky Phil]

5 hours ago, Chris Wilson said:

So Phil, all of your bolts and screws are titanium?

I am only replacing bolts to covers that allow maintenance and as noted, at low torque settings or two finger tight leverage.

Things like sump, alternator cover, rack mounts, handlebar mounted equipment etc.

I like the fact that they have a high Rockwell number as I detest turning out the head of an Allen key bolt.

Chris.

Yes pretty much all except the 10mm suspension bolts and engine mount bolts. If you turn the heads out on a titanium fastener you're doing something wrong. The beauty of them is they look exactly the same after 50 years as they did the day they were made. If your keeping your bike long term they are worth the money and if you don't then you just spend an hour or so refitting the original bolts when you sell it and use them on the next bike. The majority of fasteners on just about all bikes is M6X25. I can tell you one thing, aircraft don't use any stinking SS fasteners.

I'd use a passive plated steel bolt over a SS one every day of the week. 

Ciao 

[Chris Wilson]

Thanks for all the advice.

But please accept that in over half a century of riding motorcycles I have never had an issue with stainless on engine covers.

Will report back if my sump falls off but with 14 bolts holding on something that is about 300mm square I think that overkill comes to mind.

Chris.

[footgoose]

50 minutes ago, Chris Wilson said:

Thanks for all the advice.

But please accept that in over half a century of riding motorcycles I have never had an issue with stainless on engine covers.

Will report back if my sump falls off but with 14 bolts holding on something that is about 300mm square I think that overkill comes to mind.

Chris.

I have used s/s fasteners on all my bikes since forever. I learned early on to not rely on them for high torque spec applications. Also to make sure threads are de-burred and if the fit is tight into alm, I won't use it there either. Hard metal cuts soft metal, only takes once to learn that one. S/S in construction applications have shown them to be soft and easily broken when torqued a bit too far. Small or shallow allen head will round out easily and as has been said, use snug fitting wrenches.

They work great for all bodywork, controls, footrests, switch-gear, number plate, etc where you normally get annoying rusty bolts.

[docc]

While I’ve been careful to apply a good coat of grease to the SS threads to prevent the galvanic corrosion, the apparent fact that it will be the aluminum that is lost, not the cheaper and easier to replace SS fastener,  steered me away from SS in aluminum.

Does titanium not have this same corrosive characteristic in aluminum?

[Lucky Phil]

1 hour ago, docc said:

While I’ve been careful to apply a good coat of grease to the SS threads to prevent the galvanic corrosion, the apparent fact that it will be the aluminum that is lost, not the cheaper and easier to replace SS fastener,  steered me away from SS in aluminum.

Does titanium not have this same corrosive characteristic in aluminum?

Not sure docc as I try and avoid venturing into the Periodic table and "theoretical outcomes" if my personal experience indicates it's not an issue. Titanium is 22 aluminium is 13, is that bad? Uncoated Titanium can "gall" against itself as in a TI nut on a Ti axle but I've never had an issue on aluminium. Having said that it's recommended to use a copper based anti seize on the threads which I always do. You may remember I used a bit of Ti for bolts and bushes I machined up for my tank mount on the V10 Sport. I'm also considering making Titanium axles for my bike. I've priced the raw material and it's not a massive cost so if I can locate some KT forks I'll do that.

Ciao    

[docc]

I've been schooled in the Periodic Table of the Elements, but for other reasons. I might venture that Galvanic Effect cannot be predicted by the difference in the Atomic Number, but something more to do with differences in the electrons in the outer shell(s) of the atom's electron cloud. I waded pretty heavily out of my pay grade, there, so take that as some sort of cocktail party talk.

There are charts of Galvanic Compatibility.  Stainless steel and aluminum are considered a poor compatibility choice in this regard, even in high humidity away from salt. Notice the extremely low reactivity between aluminum and cadmium:

https://elnamagnetics.com/wp-content/uploads/catalogs/Leadertech/Galvanic-Potential-Differneces.pdf

 

 

[fotoguzzi]

Interesting.. can't hardly beat aluminum and steel.

[Chris Wilson]

Sounds like my Roper windage plate that is made of stainless is destined to be one huge anode then if the current flows along those 14 bolts to the case!